The present invention relates to improvements in so-called spreader rolls for webs of textile material or the like. More particularly, the invention relates to improvements in spreader rolls of the type wherein a flexible tubular envelope (preferably a hose made of elastomeric material) surrounds an arcuate supporting structure which is rotated by or rotates the envelope.
The tubular envelopes (hereinafter called hoses) of conventional spreader rolls are slipped onto a set or row of annular supporting elements in the form of rollers or wheels which rotate on a rigid stationary arcuate shaft. Antifriction bearings are installed between the supporting elements and the shaft to insure that the supporting elements encounter little resistance to rotation with respect to the shaft regardless of whether the supporting elements receive torque from a web of textile material or the like or from a separate drive. The end portions of the hose are secured to the outermost supporting elements.
The just described conventional spreader rolls exhibit a number of serious drawbacks. Thus, the initial cost is very high because at least one antifriction bearing (e.g., a ball bearing) must be provided for each and every supporting element. Since the shaft is normally long, the number of supporting elements and antifriction bearings is quite substantial. Secondly, the transmission of torque from a discrete drive to the supporting elements presents many problems because the shaft is stationary and, therefore, the output means of the drive can transmit torque only to one or both outermost supporting elements (the remaining supporting elements are fully confined in the interior of the hose). In addition, the maintenance cost of conventional spreader rolls is extremely high because the entire roll must be dismantled whenever it becomes necessary to gain access to one or moe supporting elemments and/or antifriction bearings. When the temperature in the interior of the hose deviates from the temperature of the surrounding air, the roll sucks air and moisture into the hose. The condensate attacks the antifriction bearings so that the bearings must be inspected and replaced at frequent intervals. In order to gain access to the bearings, workmen must disengage the ends of the hose from the nearest supporting elements, remove the hose, and thereupon remove one or more supporting elements and their bearings if the damaged bearing is not interposed between the shaft and one of the outermost supporting elements. Penetration of air and moisture into the interior of the hose cannot be prevented because the shaft is stationary and, therefore, each and every supporting element must be free to rotate on the shaft.